The present invention relates to a sealable vial and a mold and a process for making the vial in the mold. More particularly, the present invention relates to a sealable vial and cap and mold therefor, wherein the vial is sealed closed within the mold.
Vials of the type to which the present invention relates are generally injection-molded plastic vials that have caps adapted to seal the vial closed with a substantially hermetic seal. The cap may or may not be integrally connected to the vial, but is preferably joined thereto with a small flange. It is important to maintain the sterility of the interior of the vial prior to use. Accordingly, in order to maintain the sterility of the interior of the vial, the cap must be closed onto the vial while the vial is in an aseptic environment.
The vial itself is preferably formed from a thermoplastic material, and is essentially cylindrical in shape, with an integrally formed bottom. Such vials are used to collect samples, e.g., in the dairy industry. The caps are often sealed on to the vial after formation in a separate step. Under certain conditions, that step must be done under aseptic conditions and must ensure a tight, hermetic seal between the cap and the vial.
The cap includes a circular, flat center portion having a rim extending perpendicularly from the outer edge thereof. The rim is intended to fit over the upper edge of the outer wall of the vial in a sealing manner. A ridge may be formed on the inside of the cap rim to enhance the seal of the cap to the vial.
Applicant developed a concept for attempting to seat the cap onto the vial while the vial is still within the mold. In this way, the heat of the molding process could be utilized to maintain sterility during closing thereby eliminating additional steps and reducing costs and time of production of finished sealed vials. In order to effect sealing in the mold, Applicant designed a mold with several moving parts. A first part of the mold is designed to be separated from a main portion of the mold in order to allow the vial to be closed by the cap and to allow the vial to be ejected from the mold.
While the first part of the mold is separated from the main portion, a second mold part rotates on pivots to transfer the cap from its original position in the mold to a position where it is sealed closed on the vial. Once the cap is positioned on the vial, the second mold part swings back to its original position and the vial with the cap seated thereon is then ejected from the main portion of the mold, preferably by an air poppet located near the sprue gate.
After the second mold part has been returned to its original position, and after the vial has been ejected from the mold, the first part of the mold is returned to the main portion of the mold to await the beginning of a new cycle.
Applicant's initial attempts at producing and using a mold that seals the cap to the vial were not totally satisfactory. A particular problem with the mold for the manufacture of the vials is that occasionally the first part of the mold is returned to the main portion of the mold before the second part of the mold is completely reset. As a result, the first mold part strikes the second part, damaging either or both of the mold parts. The failure of the second mold part to return to its initial position may be caused by the second mold part sticking to the vial cap, or other factors delaying the resetting of the second mold part. Other unidentified causes may also contribute to the two mold parts striking each other.
Another problem with the mold is that gases mixed with the molten plastic are not able to escape from the mold cavity during the injection process. As a result, the gases remain with the plastic and form bubbles or weak spots in the molded vials.
An additional problem with the molds is that elements in the first part of the mold are partially separated by a spring during the ejection of the vial from the mold. Because of the distance the elements are separated, excessive wear causes the spring to fail with an undesirable frequency.
A further problem with the original mold is that the vial-ejecting poppet does not produce a strong enough burst of air to always eject the vial from the mold.
A further, serious problem with the vials encountered during development of the present invention is that during automated assembly, the vial cap does not always seat itself properly on the vial. If the vial is not properly sealed closed while the vial is still in the mold, sterility is not maintained. In certain situations, the cap or vial is actually damaged during the seating process. In either case, the product is not usable.
Applicant has continued to experiment and develop a fully operational mold and a sealed vial made therein which overcomes the deficiencies of Applicant's prior mold system.
Accordingly, it is an object of the present invention to provide a vial with a cap that is able to be seated easily on the vial while the vial is in the mold.
It is another object of the present invention to provide a mold for the manufacture of vials and vial caps wherein the cap may be seated on the vial by automated means with a high degree of reliability while the vial is in the mold.
It is yet another object of the present invention to provide in a mold for the manufacture of vials and vial caps, an arrangement for preventing one portion of the mold from striking and damaging another portion of the mold.
Still another object of the present invention is to provide a seal arrangement for a vial and vial cap that does not significantly impede the seating of the cap onto the vial.
It is another object of the present invention to provide a mold for the manufacture of vials and vial caps wherein gases released from the molten plastic are able to escape from the mold during the injection process.
It is still another object of the present invention to position the vial-ejecting poppet to maximize the effectiveness of the air emitted therefrom.
Still yet another object of the present invention to alleviate stress on springs contained within the mold.
It is still another object of the present invention to provide a seal arrangement for a vial and vial cap that has a high degree of reliability.
In view of these objects, it was determined that if certain modifications were made to the experimental vial mold, some of which affect the shape of the vial, dramatic increases in product quality and improved mold operation resulted.
Accordingly, in an effort to improve the quality of the vial and to increase the productivity of the mold, certain changes were made. These changes individually and collectively have produced a mold, a process of operating the mold and a sealed vial that are markedly better and more consistent than Applicant's prior efforts. These changes include but are not limited to the following:
A radius was formed in the mold at the region of the top of the vial wall, the effect of the radius being to form a smooth transition between the vial interior wall and the end surface of the vial wall.
The taper of the mold forming the interior of the vial was changed from about 1/2.degree. to about 3/4.degree..
The tip of the annular seal within the vial cap was rounded with a slight radius.
The intersection between different regions in the interior surface of the vial cap rim has been rounded with a slight break.
Vents have been added to the mold to allow gases trapped within the molten plastic to escape.
The air poppet was rotated 90.degree. so that the air stream emitted therefrom is directed toward the vial.
In accordance with additional preferred embodiments of the present invention, a rack and pinion gear system is used to pivot the second mold part for improved control. Further, a safety switch is used to indicate when the second mold part is reset to avoid unwanted engagement of mold parts. In addition, extensions of a press means are used, instead of springs, to temporarily separate the stripper plate from the end plate.
While these features are illustrative, the various combinations of features that comprise Applicant's invention are set out in the attached claims.